Organic light emitting materials

ABSTRACT

Novel phosphorescent metal complexes containing 2-phenylisoquinoline ligands with at least two substituents on the isoquinoline ring are provided. The disclosed compounds have low sublimation temperatures that allow for ease of purification and fabrication into a variety of OLED devices.

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, The University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to metal complexes containing heterocyclicligands with at least two substituents on the heterocyclic ligand. Thesemetal complexes are suitable for use in OLED devices.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

In one aspect, a compound having the formula:

Formula I is provided.In the compound of Formula I, M is a metal having an atomic weighthigher than 40, L is a second ligand, m is the maximum coordinationnumber of the metal M, d is the denticity of L, and n is at least 1. R₁is independently selected for each ligand and represents di, tri, tetra,penta substitutions, or no substitution. Each of R₁ is independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, germyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

At least two of R₁ is independently selected from two to six carboncontaining alkyl, silyl, germyl, cycloalkyl, and combinations thereof.R₂ may represent mono, di, tri, tetra substitutions, or no substitution,and each of R₂ is independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one aspect, R₁ represents di-substitution. In one aspect, R₁represents di-alkyl substitution. In another aspect, R₁ represents silylor germyl substitution.

In one aspect, the compound has the formula:

wherein R₃ and R₄ are alkyl.

In one aspect, the compound has the formula:

In one aspect, R₁ is independently selected from the group consisting ofCH(CH₃)₂, CH₂CH(CH₃)₂, CH₂C(CH₃)₃, cyclopentyl, cyclohexyl, ethyl,trimethylsilyl, triethylsilyl, triisopropylsilyl, trimethylgermyl,triethylgermyl, and triisopropylgermyl.

In one aspect, n M is Ir. In one aspect, n is 2. In one aspect, L is amonoanionic bidentate ligand. In one aspect, L is

andR_(x), R_(y), and R_(z) are each independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof.

In one aspect, R_(x), R_(y), and R_(z) are independently selected fromthe group consisting of alkyl, hydrogen, deuterium, and combinationsthereof.

In one aspect, R_(z) is hydrogen or deuterium, and R_(x) and R_(y) areindependently selected from the group consisting of methyl, CH(CH₃)₂,and CH₂CH(CH₃)₂.

In one aspect, the compound has the formula:

In one aspect, the compound is selected from Compound 1-Compound 50.

In one aspect, a first device is provided. The first device comprises afirst organic light emitting device, further comprising an anode, acathode, and an organic layer, disposed between the anode and thecathode, comprising a compound having the formula:

In the compound of Formula I, M is a metal having an atomic weighthigher than 40, L is a second ligand, m is the maximum coordinationnumber of the metal M, d is the denticity of L, and n is at least 1. R₁is independently selected for each ligand and represents di, tri, tetra,penta substitutions, or no substitution. Each of R₁ is independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, germyl, alkenyl, cycloalkenyl; heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

At least two of R₁ is independently selected from two to six carboncontaining alkyl, silyl, germyl, cycloalkyl, and combinations thereof.R₂ may represent mono, di, tri, tetra substitutions, or no substitution,and each of R₂ is independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one aspect, the first device is a consumer product. In one aspect,the first device is an organic light-emitting device. In one aspect, theorganic layer is an emissive layer and the compound is a non-emissivedopant. In one aspect, the organic layer further comprises a host.

In one aspect, the host is a metal 8-hydroxyquinolate.

In one aspect, the host is selected from the group consisting of:

and combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows a compound of Formula I.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, and a cathode 160. Cathode 160 is acompound cathode having a first conductive layer 162 and a secondconductive layer 164. Device 100 may be fabricated by depositing thelayers described, in order. The properties and functions of thesevarious layers, as well as example materials, are described in moredetail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporatedby reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 now U.S.Pat. No. 7,431,968, to Forrest et al., which is incorporated byreference in its entirety, and deposition by organic vapor jet printing(OVJP), such as described in U.S. patent application Ser. No.10/233,470, which is incorporated by reference in its entirety. Othersuitable deposition methods include spin coating and other solutionbased processes. Solution based processes are preferably carried out innitrogen or an inert atmosphere. For the other layers, preferred methodsinclude thermal evaporation. Preferred patterning methods includedeposition through a mask, cold welding such as described in U.S. Pat.Nos. 6,294,398 and 6,468,819, which are incorporated by reference intheir entireties, and patterning associated with some of the depositionmethods such as ink jet and OVJD. Other methods may also be used. Thematerials to be deposited may be modified to make them compatible with aparticular deposition method. For example, substituents such as alkyland aryl groups, branched or unbranched, and preferably containing atleast 3 carbons, may be used in small molecules to enhance their abilityto undergo solution processing. Substituents having 20 carbons or moremay be used, and 3-20 carbons is a preferred range. Materials withasymmetric structures may have better solution processability than thosehaving symmetric structures, because asymmetric materials may have alower tendency to recrystallize. Dendrimer substituents may be used toenhance the ability of small molecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, medical monitors, televisions,billboards, lights for interior or exterior illumination and/orsignaling, heads up displays, fully transparent displays, flexibledisplays, laser printers, telephones, cell phones, personal digitalassistants (PDAs), laptop computers, digital cameras, camcorders,viewfinders, micro-displays, vehicles, a large area wall, theater orstadium screen, or a sign. Various control mechanisms may be used tocontrol devices fabricated in accordance with the present invention,including passive matrix and active matrix. Many of the devices areintended for use in a temperature range comfortable to humans, such as18 degrees C. to 30 degrees C., and more preferably at room temperature(20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, aromatic group, and heteroaryl are known tothe art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32,which are incorporated herein by reference.

In one embodiment, a compound having the formula:

is provided.In the compound of Formula I, M is a metal having an atomic weighthigher than 40, L is a second ligand, m is the maximum coordinationnumber of the metal M, d is the denticity of L, and n is at least 1. By“denticity” it is meant that d numerically represents the number ofbonds a second ligand L makes with metal M. Thus, if L is a monodentateligand, then d is 1, if L is a bidentate ligand, d is 2, etc. L can beone or more ligands, and when L represents more than one ligand, theligands can be the same or different.

R₁ is independently selected for each ligand and represents di, tri,tetra, penta substitutions, or no substitution. Each of R₁ isindependently selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, germyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

At least two of R₁ is independently selected from two to six carboncontaining alkyl, silyl, germyl, cycloalkyl, and combinations thereof.R₂ may represent mono, di, tri, tetra substitutions, or no substitution,and each of R₂ is independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

It has been unexpectedly discovered that substitution at two or more ofpositions (i.e. R₁ represents at least di-substitution) on theheterocyclic ring in the compound of Formula I results in compounds withdesirable properties. These properties enable OLED devices thatincorporate compounds of Formula I to have improved properties such ashigher efficiency and longer lifetime. Substitution of two or morepositions as described above also results in compounds with loweredsublimation temperatures despite the fact that these compounds havehigher molecular weights than unsubstituted or mono-substitutedcompounds, where the mono-substitution is on the heterocyclic ring.Without being bound by theory, it is believed that this decrease insublimation temperature may be the result of decreased or less efficientmolecular stacking in the solid state, thereby decreasing the energyrequired to disrupt the crystal lattice and resulting in decreasedsublimation temperatures. Lower sublimation temperatures advantageouslyallow for easier purification of compounds of Formula I and betterthermal stability in manufacturing.

In one embodiment, R₁ represents di-substitution. In one embodiment, R₁represents di-alkyl substitution. In another embodiment, R₁ representssilyl or germyl substitution.

In one embodiment, the compound has the formula:

wherein R₃ and R₄ are alkyl.

In one embodiment, the compound has the formula:

In one embodiment, R₁ is independently selected from the groupconsisting of CH(CH₃)₂, CH₂CH(CH₃)₂, CH₂C(CH₃)₃, cyclopentyl,cyclohexyl, ethyl, trimethylsilyl, triethylsilyl, triisopropylsilyl,trimethylgermyl, triethylgermyl, and triisopropylgermyl.

In one embodiment, n M is Ir. In one embodiment, n is 2. In oneembodiment, L is a monoanionic bidentate ligand. In one embodiment, L is

andR_(x), R_(y), and R_(z) are each independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof.

In one embodiment, R_(x), R_(y), and R_(z) are independently selectedfrom the group consisting of alkyl, hydrogen, deuterium, andcombinations thereof.

In one embodiment, R_(z) is hydrogen or deuterium, and R_(x) and R_(y)are independently selected from the group consisting of methyl,CH(CH₃)₂, and CH₂CH(CH₃)₂.

In one embodiment, the compound has the formula:

In one embodiment, the compound is selected from the group consistingof:

In one embodiment, a first device is provided. The first devicecomprises a first organic light emitting device, further comprising ananode, a cathode, and an organic layer, disposed between the anode andthe cathode, comprising a compound having the formula:

In the compound of Formula I, M is a metal having an atomic weighthigher than 40, L is a second ligand, m is the maximum coordinationnumber of the metal M, d is the denticity of L, and n is at least 1. R₁is independently selected for each ligand and represents di, tri, tetra,penta substitutions, or no substitution. Each of R₁ is independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, germyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

At least two of R₁ is independently selected from two to six carboncontaining alkyl, silyl, germyl, cycloalkyl, and combinations thereof.R₂ may represent mono, di, tri, tetra substitutions, or no substitution,and each of R₂ is independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one embodiment, the first device is a consumer product. In oneembodiment, the first device is an organic light-emitting device. In oneembodiment, the organic layer is an emissive layer and the compound is anon-emissive dopant. In one embodiment, the organic layer furthercomprises a host.

In one embodiment, the host is a metal 8-hydroxyquinolate.

In one embodiment, the host is selected from the group consisting of:

and combinations thereof.

Device Examples

All example devices were fabricated by high vacuum (<10⁻⁷ Torr) thermalevaporation (VTE). The anode electrode is 1200 Å of indium tin oxide(ITO). The cathode consisted of 10 Å of LiF followed by 1000 Å of Al.All devices are encapsulated with a glass lid sealed with an epoxy resinin a nitrogen glove box (<1 ppm of H₂O and O₂) immediately afterfabrication, and a moisture getter was incorporated inside the package.

The organic stack of the device examples consisted of sequentially, fromthe ITO surface, 100 Å of Compound A as the hole injection layer (HIL),400 Å of 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD) as thehole transporting layer (HTL), 300 Å of the compound of Formula I dopedin with BAlq as host with from 4 to 12 wt % of an iridium-containingphosphorescent compound as the emissive layer (EML), 450 or 550 Å ofAlq₃ (tris-8-hydroxyquinoline aluminum) as the electron transport layer(ETL). Comparative Examples with Compound B and C were fabricatedsimilarly to the Device Examples except that the Compound B and C wereused as the emitters in the EML.

The device results and data are summarized in Tables 1, 2, and 3 fromthose devices. As used herein, Compounds A, B, and C have the followingstructures:

TABLE 1 Device structures of invention compounds and comparativecompounds Example HIL HTL EML (300 Å, doping %) BL ETL ComparativeCompound A 100 Å NPD 400 Å BAlq Compound B 6% None Alq 550 Å Example 1Comparative Compound A 100 Å NPD 400 Å BAlq Compound B 9% None Alq 550 ÅExample 2 Comparative Compound A 100 Å NPD 400 Å BAlq Compound B 12%None Alq 550 Å Example 3 Comparative Compound A 100 Å NPD 400 Å BAlqCompound C 6% None Alq 550 Å Example 4 Comparative Compound A 100 Å NPD400 Å BAlq Compound C 9% None Alq 550 Å Example 5 Comparative Compound A100 Å NPD 400 Å BAlq Compound C 12% None Alq 550 Å Example 6 Example 1Compound A 100 Å NPD 400 Å BAlq Compound 1 4% None Alq 550 Å Example 2Compound A 100 Å NPD 400 Å BAlq Compound 1 6% None Alq 550 Å Example 3Compound A 100 Å NPD 400 Å BAlq Compound 1 8% None Alq 550 Å Example 4Compound A 100 Å NPD 400 Å BAlq Compound 1 6% BAlq 100 Å Alq 450 ÅExample 5 Compound A 100 Å NPD 400 Å BAlq Compound 2 5% None Alq 550 ÅExample 6 Compound A 100 Å NPD 400 Å BAlq Compound 2 7% None Alq 550 ÅExample 7 Compound A 100 Å NPD 400 Å BAlq Compound 2 10% None Alq 550 ÅExample 8 Compound A 100 Å NPD 400 Å BAlq Compound 2 7% BAlq 100 Å Alq450 Å Example 9 Compound A 100 Å NPD 400 Å BAlq Compound 3 5% None Alq550 Å Example 10 Compound A 100 Å NPD 400 Å BAlq Compound 3 7% None Alq550 Å Example 11 Compound A 100 Å NPD 400 Å BAlq Compound 3 10% None Alq550 Å Example 12 Compound A 100 Å NPD 400 Å BAlq Compound 3 7% BAlq 100Å Alq 450 Å Example 13 Compound A 100 Å NPD 400 Å BAlq Compound 22 4%None Alq 550 Å Example 14 Compound A 100 Å NPD 400 Å BAlq Compound 22 6%None Alq 550 Å Example 15 Compound A 100 Å NPD 400 Å BAlq Compound 22 8%None Alq 550 Å Example 16 Compound A 100 Å NPD 400 Å BAlq Compound 22 6%BAlq 100 Å Alq 450 Å

TABLE 2 VTE device results λ_(max) FWHM Voltage LE EQE PE LT80 x y (nm)(nm) (V) (Cd/A) (%) (Im/W) % (h) Comparative 0.693 0.304 635 63 10 10.818.3 3.4 606 Example 1 Compound B Comparative 0.695 0.303 637 66 9.910.5 18.5 3.3 799 Example 2 Compound B Comparative 0.693 0.304 637 669.5 10.0 17.7 3.3 948 Example 3 Compound B Comparative 0.690 0.306 63363 10.3 12.2 19.1 3.7 650 Example 4 Compound C Comparative 0.692 0.306635 65 9.4 11.8 19.3 3.9 475 Example 5 Compound C Comparative 0.6910.306 635 66 8.9 11.5 19.0 4.1 700 Example 6 Compound C Example 1 0.6870.309 628 52 10.1 12.5 17.8 3.9 178 Compound 1 Example 2 0.689 0.307 63056 9.9 12.6 18.7 4.0 174 Compound 1 Example 3 0.691 0.306 632 56 9.512.4 19.0 4.1 171 Compound 1 Example 4 0.690 0.307 630 56 10.9 12.5 18.63.6 160 Compound 1 Example 5 0.687 0.311 630 58 9.5 13.8 19.6 4.6 350Compound 2 Example 6 0.688 0.310 630 60 9.5 13.8 19.9 4.5 360 Compound 2Example 7 0.688 0.310 632 62 8.8 13.1 19.4 4.7 400 Compound 2 Example 80.687 0.309 630 58 10.5 12.9 18.7 3.9 360 Compound 2 Example 9 0.6850.313 626 58 9.5 14.8 19.8 4.9 232 Compound 3 Example 10 0.687 0.311 62862 8.9 14.5 20.5 5.1 260 Compound 3 Example 11 0.688 0.310 630 64 8.114.0 20.3 5.4 235 Compound 3 Example 12 0.687 0.311 628 60 9.7 14.5 20.24.7 280 Compound 3 Example 13 0.684 0.313 626 48 9.3 14.8 18.8 5.0 192Compound 22 Example 14 0.686 0.311 626 52 8.8 14.3 19.1 5.1 170 Compound22 Example 15 0.686 0.311 628 52 8.2 14.2 19.2 5.4 122 Compound 22Example 16 0.686 0.312 626 50 9.3 14.8 19.6 5.0 210 Compound 22

Table 2 is a summary of the device data. The luminous efficiency (LE),external quantum efficiency (EQE) and power efficiency (PE) weremeasured at 1000 nits, while the lifetime (LT_(80%)) was defined as thetime required for the device to decay to 80% of its initial luminanceunder a constant current density of 40 mA/cm².

From Table 2, it can be seen that the EQE, LE and PE of Compounds 1, 2,3, and 22, which are compounds of Formula I, at three different dopingconcentrations (without a hole blocking layer) are all higher than thoseof Comparative Compounds B and C. For example, when the device has thesame 6% emitter doping concentration without the hole blocking layer,Compound 22 has EQE of 19.1%, LE of 14.3 Cd/A, and PE of 5.1 lm/W,respectively. This compares to Comparative Compounds B and C which haveEQE of 18.3 and 19.1%, LE of 10.8 and 12.2 Cd/A, and PE of 3.4 and 3.7lm/W, respectively. The device results indicate that, surprisingly, thedi-alkyl substituted Compounds 1, 2, 3 and 22 are more efficient thancomparative compound B and mono-substituted compound C. It can also beenseen from Table 2 that the FWHM (full width at half maximum) values ofCompound 1, 2, 3, and 22 under different device structures are in therange of 48-64 nm, which is significantly narrower than those ofCompounds B and C, which are in the range of 63-66 nm. Smaller FWHMvalues are often desirable in display applications. Thus, the use ofcompounds of Formula I, which are at least di-substituted on theheterocyclic ring contained therein can improve device performance,because these compounds have high EQE, LE, PE values and low FWHMvalues.

TABLE 3 Comparison of Sublimation Temperatures Temperature SublimationDifference Temperature Relative to Compounds (° C.) Compound B

210 Compound B

218 −8 Compound C

197 13 Compound 1

202  8 Compound 2

204  6 Compound 3

194 16 Compound 22

It can be seen that di-substitution on the heteroaromatic ring incompounds of Formula I can decreases the sublimation temperature ofcomplex as shown in Table 3. It was surprisingly discovered thatdi-substituted compounds of Formula I had lower sublimation temperaturesthan un-substituted or mono-substituted compounds. For example, Compound22 had a significantly lower sublimation temperature than ComparativeCompound B (194° C. vs 210° C.) despite the fact that Compound 22 has ahigher molecular weight than Comparative Compound B.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial. Examples of the material include, but not limit to: aphthalocyanine or porphryin derivative; an aromatic amine derivative; anindolocarbazole derivative; a polymer containing fluorohydrocarbon; apolymer with conductivity dopants; a conducting polymer, such asPEDOT/PSS; a self-assembly monomer derived from compounds such asphosphonic acid and sliane derivatives; a metal oxide derivative, suchas MoO_(x); a p-type semiconducting organic compound, such as1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and across-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, butnot limit to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting aromatichydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl,triphenylene, naphthalene, anthracene, phenalene, phenanthrene,fluorene, pyrene, chrysene, perylene, azulene; group consisting aromaticheterocyclic compounds such as dibenzothiophene, dibenzofuran,dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene,benzoselenophene, carbazole, indolocarbazole, pyridylindole,pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole,oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine,pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine,indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole,benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline,quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine,phenazine, phenothiazine, phenoxazine, benzofuropyridine,furodipyridine, benzothienopyridine, thienodipyridine,benzoselenophenopyridine, and selenophenodipyridine; and groupconsisting 2 to 10 cyclic structural units which are groups of the sametype or different types selected from the aromatic hydrocarbon cyclicgroup and the aromatic heterocyclic group and are bonded to each otherdirectly or via at least one of oxygen atom, nitrogen atom, sulfur atom,silicon atom, phosphorus atom, boron atom, chain structural unit and thealiphatic cyclic group. Wherein each Ar is further substituted by asubstituent selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the groupconsisting of:

k is an integer from 1 to 20; X¹ to X⁸ is C (including CH) or N; Ar¹ hasthe same group defined above.

Examples of metal complexes used in HIL or HTL include, but not limit tothe following general formula:

M is a metal, having an atomic weight greater than 40; (Y¹-Y²) is abidentate ligand, Y¹ and Y² are independently selected from C, N, O, P,and S; L is an ancillary ligand; m is an integer value from 1 to themaximum number of ligands that may be attached to the metal; and m+n isthe maximum number of ligands that may be attached to the metal.

In one aspect, (Y¹-Y²) is a 2-phenylpyridine derivative.

In another aspect, (Y¹-Y²) is a carbene ligand.

In another aspect, M is selected from Ir, Pt, Os, and Zn.

In a further aspect, the metal complex has a smallest oxidationpotential in solution vs. Fc⁺/Fc couple less than about 0.6 V.

Host:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingmaterial, and may contain a host material using the metal complex as adopant material. Examples of the host material are not particularlylimited, and any metal complexes or organic compounds may be used aslong as the triplet energy of the host is larger than that of thedopant. While the Table below categorizes host materials as preferredfor devices that emit various colors, any host material may be used withany dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have thefollowing general formula:

M is a metal; (Y³-Y⁴) is a bidentate ligand, Y³ and Y⁴ are independentlyselected from C, N, O, P, and S; L is an ancillary ligand; m is aninteger value from 1 to the maximum number of ligands that may beattached to the metal; and m+n is the maximum number of ligands that maybe attached to the metal.

In one aspect, the metal complexes are:

(O—N) is a bidentate ligand, having metal coordinated to atoms O and N.

In another aspect, M is selected from Ir and Pt.

In a further aspect, (Y³-Y⁴) is a carbene ligand.

Examples of organic compounds used as host are selected from the groupconsisting aromatic hydrocarbon cyclic compounds such as benzene,biphenyl, triphenyl, triphenylene, naphthalene, anthracene; phenalene,phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; groupconsisting aromatic heterocyclic compounds such as dibenzothiophene,dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran,benzothiophene, benzoselenophene, carbazole, indolocarbazole,pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole,oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole,pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine,oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine,benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline,cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine,pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine,benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine;and group consisting 2 to 10 cyclic structural units which are groups ofthe same type or different types selected from the aromatic hydrocarboncyclic group and the aromatic heterocyclic group and are bonded to eachother directly or via at least one of oxygen atom, nitrogen atome,sulfur atom, silicon atom, phosphorus atom, boron atom, chain structuralunit and the aliphatic cyclic group. Wherein each group is furthersubstituted by a substituent selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one aspect, host compound contains at least one of the followinggroups in the molecule:

R¹ to R⁷ is independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof, when it is aryl or heteroaryl, it has the similardefinition as Ar's mentioned above.

k is an integer from 0 to 20.

X¹ to X⁸ is selected from C (including CH) or N.

Z¹ and Z² is selected from NR¹, O, or S.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies as compared to a similar device lacking a blocking layer.Also, a blocking layer may be used to confine emission to a desiredregion of an OLED.

In one aspect, compound used in HBL contains the same molecule or thesame functional groups used as host described above.

In another aspect, compound used in HBL contains at least one of thefollowing groups in the molecule:

k is an integer from 0 to 20; L is an ancillary ligand, m is an integerfrom 1 to 3.

ETL:

Electron transport layer (ETL) may include a material capable oftransporting electrons. Electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

In one aspect, compound used in ETL contains at least one of thefollowing groups in the molecule:

R¹ is selected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is arylor heteroaryl, it has the similar definition as Ar's mentioned above.

Ar¹ to Ar³ has the similar definition as Ar's mentioned above.

k is an integer from 0 to 20.

X¹ to X⁸ is selected from C (including CH) or N.

In another aspect, the metal complexes used in ETL contains, but notlimit to the following general formula:

(O—N) or (N—N) is a bidentate ligand, having metal coordinated to atomsO, N or N,N; L is an ancillary ligand; m is an integer value from 1 tothe maximum number of ligands that may be attached to the metal.

In any above-mentioned compounds used in each layer of the OLED device,the hydrogen atoms can be partially or fully deuterated.

In addition to and/or in combination with the materials disclosedherein, many hole injection materials, hole transporting materials, hostmaterials, dopant materials, exiton/hole blocking layer materials,electron transporting and electron injecting materials may be used in anOLED. Non-limiting examples of the materials that may be used in an OLEDin combination with materials disclosed herein are listed in Table 4below. Table 4 lists non-limiting classes of materials, non-limitingexamples of compounds for each class, and references that disclose thematerials.

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EXPERIMENTAL

Chemical abbreviations used throughout this document are as follows: Cyis cyclohexyl, dba is dibenzylideneacetone, EtOAc is ethyl acetate, DMEis dimethoxyethane, dppe is 1,2-bis(diphenylphosphino)ethane, THF istetrahydrofuran, DCM is dichloromethane, DMF is dimethylformamide,S-Phos is dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine.

Synthesis of Compound 1

Synthesis of N-(3,5-dichlorobenzylidene)-2,2-diethoxyethanamine

3,5-dichlorobenzaldehyde (51.2 g, 284 mmol), 2,2-diethoxyethanamine(38.6 g, 284 mmol) and 270 mL toluene were charged in a 500 mLthree-necked flask. The mixture was heated to reflux for 24 hours underN₂ with Dean-Stark apparatus to collect water by-product. 86 g (100%)light yellow liquid was obtained after evaporated solvent. The productwas confirmed by GC-MS and NMR and taken on to the next step withoutfurther purification.

Synthesis of 5,7-dichloroisoquinoline

Trifluoromethanesulfonic acid (15.83 g, 103 mmol) was charged in athree-necked 100 mL flask which was equipped with a Dean-Stark apparatusand addition funnel. The trifluoromethanesulfonic acid was first heatedto 120° C. and to the acid,N-(3,5-dichlorobenzylidene)-2,2-diethoxyethanamine (4 g, 13.78 mmol)dissolved in 4 mL DCM was added dropwise. After addition, the mixturewas heated for another 2 hours at 120° C., then cooled to roomtemperature, and 8 mL of MeOH was added to quench the reaction. Thereaction mixture was poured into aqueous ammonium hydroxide (120 mmol)solution, made basic with additional aqueous ammonium hydroxide, andstirred and filtered. A white solid (2.1 g, 77%) was obtained afterdistillation. The identity of the product was confirmed by GC and HPLC.A larger scale reaction with 32.2 g ofN-(3,5-dichlorobenzylidene)-2,2-diethoxyethanamine was conducted in asame way and 16.5 g (75%) of the product was obtained for next step.

Synthesis of 5,7-diisobutylisoquinoline

5,7-Dichloroisoquinoline (5.8 g, 29.3 mmol), isobutylboronic acid (8.96g, 88 mmol), dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine(0.962 g, 2.34 mmol), Pd₂(dba)₃ (0.536 g, 0.586 mmol), K₃PO₄ (21.8 g,103 mmol), 150 mL toluene and 15 mL water were charged in a flask. Thereaction mixture was purged by bubbling N₂ for 30 minutes then heated toreflux overnight. GC-MS analysis showed that the reaction was complete.Silica gel chromatography with 15% ethyl acetate in hexane (v/v) aselutent resulted in 6.7 g (95%) of the product.

Synthesis of 1-(3,5-dimethylphenyl)-5,7-diisobutylisoquinoline

5,7-Diisobutylisoquinoline (7.4 g, 30.7 mmol) in 50 mL dry THF and wasadded to (3,5-dimethylphenyl)magnesium bromide (100 mL, 50.0 mmol)dropwise at room temperature and allowed to stir for 16 hours, afterwhich the reaction mixture was heated to reflux for 5 hours. GC and HPLCanalysis indicated the reaction was complete, but contained a smallamount of reduced byproducts which were converted to the desired productby treatment with DDQ in THF for few minutes. After aqueous workup, 6.5g (61.4%) of product was obtained.

Synthesis of Iridium Dimer

1-(3,5-dimethylphenyl)-5,7-diisobutylisoquinoline (6.0 g, 17.37 mmol)and IrCl₃.H₂O (2.57 g, 6.95 mmol), 90 mL 2-ethoxylethanol and 30 mLwater were charged in a 250 mL flask. The reaction mixture was heated toreflux under nitrogen for 19 hours. 3.1 g (24.3%) of dimer was obtainedafter filtration and washing with methanol, which was used for next stepwithout further purification.

Synthesis of Compound 1

2-(3,5-dimethylphenyl)-5,7-diisobutylquinoline iridium dimer (1.5 g,0.82 mmol), 2,4-pentanedione (1.63 g, 16.36 mmol), Na₂CO₃ (1.73 g, 16.36mmol) and 2-ethoxyethanol (60 mL) were charged in a 250 flask andstirred at room temperature for 72 hours. The resulting precipitate wasfiltered and washed with methanol. The solid was further purified bypassing it through a silica gel plug (that was pretreated with 15%triethylamine in hexanes). 0.55 g (34.3%) of product was obtained afterworkup. The identity of the product was confirmed by LC-MS.

Synthesis of Compound 2

Synthesis of 5,7-di(prop-1-en-2-yl)isoquinoline

5,7-Dichloroisoquinoline (5.1 g, 25.8 mmol),4,4,5,5-tetramethyl-2-(prop-1-en-2-yl)-1,3,2-dioxaborolane (9.95 g, 59.2mmol), dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine(0.846 g, 2.06 mmol), Pd₂(dba)₃ (0.472 g, 0.515 mmol), K₃PO₄ (19.13 g,90 mmol), 100 mL toluene and 10 mL water were charged in a flask. Thereaction mixture was purged by bubbling N₂ for 30 minutes then heated toreflux overnight. GC-MS analysis showed that the reaction was complete.5.1 g (91%) of product was obtained after silica gel columnchromatography and confirmed by GC-MS.

Synthesis of 5,7-diisopropyl)isoquinoline

5,7-Di(prop-1-en-2-yl)isoquinoline (5.1 g, 24.37 mmol) was dissolved in50 mL EtOH in a glass bottle and purged with N₂ for 30 minutes. To thesolution, 10% Pd/C (1.3 g, 1.218 mmol) was added into the bottle undernitrogen. Hydrogenation was conducted for 4 hours, after which GC-MSanalysis indicated the reaction was complete.

Synthesis of 1-(3,5-dimethylphenyl)-5,7-diisopropylisoquinoline

5,7-diisopropylisoquinoline (3.1 g, 14.5 mmol) in 50 mL dry THF and wasadded with 0.5 M (3,5-dimethylphenyl)magnesium bromide THF solution (50mL, 25.0 mmol) dropwise at room temperature and allowed to stir for 16hours, after which the reaction mixture was heated to reflux for 5hours. GC and HPLC analysis indicated the reaction was complete, butcontained a small amount of reduced byproducts which were converted tothe desired product by treatment with DDQ in THF for few minutes. Afteraqueous workup, 2.4 g (52%) of product was obtained.

Synthesis of Iridium Dimer

1-(3,5-Dimethylphenyl)-5,7-diisopropylisoquinoline (2.4 g, 7.56 mmol)and IrCl₃.H₂O (1.167 g, 3.15 mmol), 45 mL 2-ethoxylethanol and 15 mLwater were charged in a 250 mL flask. The reaction mixture was heated toreflux under nitrogen for 19 hours. After cooling the reaction,filtration, and washing with methanol, 1.2 g (44.2%) of dimer wasobtained, which was used for next step without further purification.

Synthesis of Compound 2

2-(3,5-Dimethylphenyl)-5,7-diisopropylquinoline iridium dimer (1.2 g,0.697 mmol), 2,4-pentanedione (0.697 g, 6.97 mmol), Na₂CO₃ (0.739 g,6.97 mmol) and 2-ethoxyethanol (40 mL) were stirred at room temperaturefor 48 hours. The precipitate was filtered and washed with methanol. Thesolid was further purified by passing it through a silica gel plug(pretreated with 15% tryethylamine in hexanes). After workup of thereaction 0.68 g (52.8%) of product was obtained, which was confirmed byLC-MS.

Synthesis of Compound 3

Synthesis of 4-Chloro-2-methylbenzoyl chloride

To a mixture of 4-chloro-2-methylbenzoic acid (24.0 g, 141 mmol) indichloromethane (20 mL) and dimethylformamide (4 mL) at room temperaturewas added dropwise oxalyl chloride (26.8 g, 258 mmol). The reaction wasstirred room temperature for 2 hours. Hexanes were added and thereaction mass was concentrated to give 4-chloro-2-methylbenzoyl chloride(26.6 g, quantitative) and used in the next step without purification.

Synthesis of 4-Chloro-2-methylbenzamide

30% Ammonium hydroxide (300 mL, 4.76 mol) was cooled in a salt ice bath.4-chloro-2-methylbenzoyl chloride (26.4 g, 140 mmol) in tetrahydrofuran(150 mL) added and stirred for 1 hr. Water was added. Crystals werefiltered off and washed with water and dried under vacuum to give4-chloro-2-methylbenzamide (20.0 g, 84% yield).

Synthesis of 4-Chloro-N-((dimethylamino)methylene)-2-methylbenzamide

A mixture of 4-chloro-2-methylbenzamide (20.8 g, 123 mmol) and1,1-dimethylmethaneamine (17.5 g, 147 mmol) in tetrahydrofuran (250 mL)was refluxed for 2.5 hours and then concentrated. The resulting crystalswere triturated in hexanes and filtered to give4-chloro-N-((dimethylamino)methylene)-2-methylbenzamide (25.7 g, 93%yield).

Synthesis of 6-Chloroisoquinolin-1-ol

A mixture of 4-chloro-N-((dimethylamino)methylene)-2-methylbenzamide(25.7 g, 114 mmol), sodium tert-butoxide (25.7 g, 267 mmol) andtetrahydrofuran (450 mL) was refluxed under N₂ for 3 hours and thenpoured into water (1 L). The pH was adjusted to 4 with aqueous HCl. Thesolids were filtered off and washed with water and dried under vacuum togive 6-chloroisoquinolin-1-ol (14.7 g, 71.6% yield).

Synthesis of 4,6-Dichloroisoquinolin-1-ol

A mixture of 6-chloroisoquinolin-1-ol (13.5 g, 75 mmol) and acetonitrile(400 mL) was heated to reflux. N-Chlorosuccinimide (10.57 g, 79 mmol) inacetonitrile (110 mL) was added dropwise. The mixture was refluxedovernight. Crystals were filtered off. The filtrate was concentrated andthe resulting crystals were washed with water and combined with theabove crystals and dried under vacuum to give4,6-dichloroisoquinolin-1-ol (14.2 g, 88% yield). It was taken onwithout analysis to the next step.

Synthesis of 4,6-Dichloroisoquinolin-1-yl trifluoromethanedsulfonate. Amixture of 4,6-dichloroisoquinolin-1-ol (14.2 g, 66.5 mmol), pyridine(10.8 mL, 133 mmol) and dichloromethane (200 mL) was cooled in an icebath. Trifluoromethanesulfonic anhydride (22.4 mL, 133 mmol) was addeddropwise. The mixture was stirred overnight at room temperature. Waterwas added and NaHCO₃ (20 g) was added slowly. The organic layer wasdried over Na₂SO₄, concentrated and flash chromatographed using silicagel chromatography (4:1 hexanes:dichloromethane, v/v) to give4,6-dichloroisoquinolin-1-yl trifluoromethanedsulfonate (3.7 g, 16%yield).

Synthesis of 4,6-Dichloro-1-(3,5-dimethylphenyl)isoquinoline

A mixture of 4,6-dichloroisoquinolin-1-yl trifluoromethanesulfonate (4.0g, 11.6 mmol), 3,5-dimthylphenyl)boronic acid (1.6 g, 10.8 g), Pd(PPh₃)₄(0.67 g, 0.58 mmol), potassium carbonate (4.79, 34.7 mmol), toluene (100mL) and water (10 mL) was purged with nitrogen and refluxed overnight.The concentrated toluene layer was chromatographed using silica gelchromatography (2:1 hexanes:dichloromethane, v/v) to give4,6-dichloro-1-(3,5-dimethylphenyl)isoquinoline (3.0 g, 92% yield).

Synthesis of 1-(3,5-Dimethylphenyl)isoquinoline

A mixture of 4,6-dichloro-1-(3,5-dimethylphenyl)isoquinoline (3.2 g,10.59 mmol), isobutylboronic acid (4.32 g, 42.4 mmol), Pd₂(dba)₃ (0.388g, 0.424 mmol),dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (0.696 g,1.694 mmol), K₃PO₄.H₂O (24.38 g, 106 mmol), toluene (133 mL) and water(11 mL) were purged with nitrogen for 30 minutes and refluxed overnight.The toluene layer was chromatographed using silica gel chromatography(100% dichloromethane to 4:1 dichloromethane:ethyl acetate, v/v) to give1-(3,5-dimethylphenyl)isoquinoline (3.3 g, 90% yield).

Synthesis of 1-(3,5-Dimethylphenyl)isoquinoline Iridium dimer

A mixture of 1-(3,5-dimethylphenyl)-4,6-diisobutylisoquinoline (3.3 g,9.55 mmol), IrCl₃.3H₂O (1.475 g, 3.98 mmol), 2-ethoxyethanol (45 mL) andwater (15 mL) were refluxed overnight and then filtered and washed withmethanol to give 1-(3,5-dimethylphenyl)isoquinoline iridium dimer (2.0g, 54.8% yield).

Synthesis of Compound 3

A mixture of 1-(3,5-dimethylphenyl)isoquinoline iridium dimer (1.2 g,0.655 mmol), pentane-2,4-dione (0.655 g, 6.55 mmol), potassium carbonate(0.905 g, 6.55 mmol) and 2-ethoxyethanol (60 mL) was stirred at roomtemperature overnight and filtered, washed with methanol andchromaographed using silica gel chromatography (4:1hexanes:dichloromethane, v/v, silica gel pre-treated withtriethylamine). The residue was dissolved in dichloromethane and2-propanol. The dichloromethane was removed on a rotoevaporator and 0.68g of crystals were filtered off and then sublimed at 230° C. to giveCompound 3 (0.32 g, 24.9%), which was confirmed by LC-MS.

Synthesis of Compound 22

Synthesis of Compound 22

A mixture of 1-(3,5-dimethylphenyl)isoquinoline iridium dimer (0.8 g,0.436 mmol), 2,6-dimethylheptane-3,5-dione (0.682 g, 4.36 mmol),potassium carbonate (0.603 g, 4.36 mmol) and 2-ethoxyethanol (60 mL)were stirred at room temperature overnight and filtered, washed withmethanol and chromaographed on silica gel (4:1 hexanes:dichloromethane,v/v, silica gel pre-treated with triethylamine). The residue wasdissolved in dichloromethane and 2-propanol. The dichloromethane wasremoved on a rotoevaporator and 0.60 g of crystals were obtained afterfiltration. It was confirmed by LC-MS.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

The invention claimed is:
 1. A compound having the formula:

wherein M is a metal having an atomic weight higher than 40; wherein Lis a second ligand; wherein m is the maximum coordination number of themetal M; wherein d is the denticity of L; wherein n is at least 1;wherein one of R₁₃, R₁₄, R₁₅, R₁₆, R₁₇, and R₁₈ is hydrogen and theremainder are independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, germyl, alkenyl, cycloalkenyl,heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylicacids, ester, nitrile, isonitrile, sulfanyl, sulfonyl, sulfonyl,phosphino, and combinations thereof; wherein at least two of R₁₃, R₁₄,R₁₅, R₁₆, R₁₇, and R₁₈ are independently selected from two to threecarbon containing alkyl, silyl, germyl, cycloalkyl, and combinationsthereof; wherein each of R₂₂, R₂₃, R₂₄, and R₂₅ is independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein atleast one of the following (i)-(ii) is true: (i) at least one of R₁₃ toR₁₈ is cycloalkyl or germyl; and (ii) at least one of R₁₃ to R₁₈ issilyl, R₂₃ and R₂₅ are alkyl, and R₂₂ and R₂₄ are hydrogen.
 2. Thecompound of claim 1, wherein two of R₁₃ to R₁₈ are alkyl substitutions.3. The compound of claim 1, wherein at least one of R₁₃ to R₁₈represents a silyl or a germyl substitution.
 4. The compound of claim 1,wherein the compound has the formula:


5. The compound of claim 1, wherein at least one of R₁₃, R₁₅, R₁₆, andR₁₈ is selected from the group consisting of ethyl and CH(CH₃)₂, or atleast one of R₁₃ to R₁₈ is selected from the group consisting ofcyclopentyl, cyclohexyl, trimethylsilyl, triethylsilyl,triisopropylsilyl, trimethylgermyl, triethylgermyl, andtriisopropylgermyl.
 6. The compound of claim 1, wherein M is Ir.
 7. Thecompound of claim 1, wherein n is
 2. 8. The compound of claim 1, whereinL is a monoanionic bidentate ligand.
 9. The compound of claim 8, whereinL is

and wherein R_(x), R_(y), and R_(z) are each independently selected fromthe group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof.
 10. The compound of claim9, wherein R_(x), R_(y), and R_(z) are independently selected from thegroup consisting of alkyl, hydrogen, deuterium, and combinationsthereof.
 11. The compound of claim 10, wherein R_(z) is hydrogen ordeuterium, and R_(x) and R_(y) are independently selected from the groupconsisting of methyl, CH(CH₃)₂, and CH₂CH(CH₃)₂.
 12. The compound ofclaim 9, wherein the compound has the formula:


13. The compound of claim 1, wherein the compound is selected from thegroup consisting of:


14. A first device comprising a first organic light emitting device,comprising: an anode; a cathode; and an organic layer, disposed betweenthe anode and the cathode, comprising a compound having the formula:

wherein M is a metal having an atomic weight higher than 40; wherein Lis a second ligand; wherein m is the maximum coordination number of themetal M; wherein d is the denticity of L; wherein n is at least 1;wherein one of R₁₃, R₁₄, R₁₅, R₁₆, R₁₇, and R₁₈ is hydrogen and theremainder are independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, germyl, alkenyl, cycloalkenyl,heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylicacids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl,phosphino, and combinations thereof; wherein at least two of R₁₃, R₁₄,R₁₅, R₁₆, R₁₇, and R₁₈ are independently selected from two to threecarbon containing alkyl, silyl, germyl, cycloalkyl, and combinationsthereof; wherein each of R₂₂, R₂₃, R₂₄, and R₂₅ is independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein atleast one of the following (i)-(ii) is true: (i) at least one of R₁₃ toR₁₈ is cycloalkyl or germyl; and (ii) at least one of R₁₃ to R₁₃ issilyl, R₂₃ and R₂₅ are alkyl, and R₂₂ and R₂₄ are hydrogen.
 15. Thefirst device of claim 14, wherein the first device is a consumer productor an organic light-emitting device.
 16. The first device of claim 14,wherein the organic layer is an emissive layer and the compound is anon-emissive dopant.
 17. The first device of claim 14, wherein theorganic layer further comprises a host.
 18. The first device of claim17, wherein the host is a metal 8-hydroxyquinolate.
 19. The first deviceof claim 17, wherein the host is selected from the group consisting of:

and combinations thereof.
 20. The first device of claim 14, wherein thecompound is selected from the group consisting of: